Group iii-a element compounds



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United States Patent 2,987,534 GROUP III-A ELEMENT COMPOUNDS Hymin Shapiro and Earl G. De Witt, Baton Rouge, La., and Jerome E. Brown, Detroit, Micln, assignors to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 25, 1958, Ser. No. 730,819

7 Claims. (Cl. 260-448) This invention relates to novel hydrocarbon group HI- A element compounds and to a process for their preparation.

Attendant with the development and evolution of the internal combustion engine for passenger car and heavyduty service, the petroleum industry has been continually called upon to eifect improvements in the antiknock quality of hydrocarbon fuels. These improvements have, in general, been brought about by two distinct methods. One of these methods comprises improvements in refining operations such as thermal and catalytic cracking and reforming or alkylating processes. The other method comprises the use of fuel additives to effect an increase in the antiknock qualities of the hydrocarbon fuels. Inasmuch as improvements in refinery techniques involve considerable capital expenditures, the use of fuel additives has attained greater and more widespread acceptance as the more effective method, particularly from the economic standpoint. The instant invention is therefore concerned with providing novel hydrocarbon group III-A element compounds suitable for use in the manufacture of hydrocarbon manganese compounds useful as additives to fuel and lubricating oils and also useful in the synthesis of other manganese compounds which are capable of improving combustion characteristics of hydrocarbon fuels and as additives to lubricating oils and greases, and the like.

' It is therefore an object of our invention to provide novel hydrocarbon group III-A element compounds. It is also an object of this invention to provide such compounds for manufacture of hydrocarbon manganese compounds which are useful as additives for liquid and solid combustion fuels, and lubricating oils and greases, 'as well as for other uses. It is likewise an object to provide a process for the preparation of novel hydrocarbon group III-A element compounds. Additional important objects of this invention will become apparent from the discussion which follows.

The above and other objects are accomplished by providing novel tris(hydrocarbon cyclomatic) group III-A element compounds in which the cyclomatic hydrocarbon radicals have from to about 17 carbon atoms and which embody axgroup of 5 carbons having the general configuration found in cyclopentadiene.

More specifically, the compounds of this invention have the general formula:

wherein R is a cyclomatic radical as defined above and M is a grouplIf-A element. The compounds of this invention can be made by a number of processes.

One suitable process is to react the group III-A element with a cyclomatic compound of the metal which is lower than the group IH-A element in the electromotive series. For example, tris(cyclopentadienyl) aluminum can be made by reacting aluminum metal with bis(cyclopentadienyl) mercury. This reaction can be carried out-at temperatures of from about 50 to 250 Patented June 6, 1961 out in inert solvent system. Particularly useful solvents are hydrocarbons, including aliphatic, aromatic and cycloaliphatic, chlorinated hydrocarbons, ethers, amines and acetals. In most cases the reaction is preferably conducted with an inert atmosphere, frequently maintained at moderate pressures, since some of these compounds are susceptible to air oxidation or react with water.

Another very suitable method for the preparation of the compounds of this invention comprises the reaction of alkali metal cyclomatic compounds with aluminum compounds, e.g. aluminum salt such as aluminum halides, alcoholates, alkanoates, and the like. This reaction can be conducted under the same general conditions as those defined above. Another process comprises the use of alkaline earth metal cyclomatic compounds with the same aluminum compounds, including the use of Grignard reagents, such as cyclopentadienyl magnesium halides.

Another suitable process for the manufacture of the compounds of this invention involves the reaction of an activated form of a group III-A element with the cyclo matic hydrocarbon directly. Thus, activated aluminum or other group III-A metal in highly subdivided form can be reacted with a cyclopentadienyl hydrocarbon to form the tris(cyclopentadienyl) hydrocarbon group "III- A element compound. In this process, a particularly desirable modification involves the initial activation of the metal with a quantity of tris(cyclomatic) hydrocarbon group HI-A element compound. More specifically, the directreaction of cyclomatic hydrocarbon with a group III-A element is conducted in the presence of a quantity of pre-prepared tris(cyclomatic) hydrocarbon group III-A element compound. In actual practice the process can be conducted continuously or batch-wise such that only a portion of the tris(cyclomatic) hydrocarbon group I[[- A element product is removed from the reactor and a portion of the product remains in the reactor with excess metal for further reaction with additional cyclomatic hydrocarbon.

When employing the compounds of our invention for use in the synthesis of other hydrocarbon metal compounds, e.g. manganese compounds, we especially prefer compounds in which at least one of the carbon-to-carbon double bonds in the cyclopentadienyl-group configuration is olefinic in nature. in other words, in this preferred embodiment not more than two carbons of the cyclopentadienyl ring should be shared with a fused aromatic I .ring such as a benzene ring. An example of one of the C., preferably in the range of 0 to 100 C. The specific .of the reactants or product. The process is best carried cyclomatic radicals of this type of embodiments is the indenyl radical. When compositions of this invention having cyclomatic radicals, with the above described characteristics, are employed in producing cyclomatic manganese compounds, the resultant manganese compounds are found to have highly desirable characteristics when used as fuel and lubricating additives.

Reference to the generic formula described above indicates that there are two types of constituents in the new composition of matter of the present invention. These are, first, the cyclomatic radicals R, which can be the same or different and, second, the elemental constituents B, A1, Ga, In and Tl. As stated previously, the cyclomatic radicals R are cyclopentadienyl-type radicals, i.e., radicals containing the cyclopentadienyl moiety. In general, such cyclomatic groups can be represented bythe four generic formulae presented hereinafter, having from 5 to about 17 carbon atoms. Thus, any substituents attached to the cyclopentadienyl group in the radical can have from 1 to to about 1-2 carbon atoms. However, radicals in which the substituents have from 1 to about 20 or more carbon atoms are also within our invention.

When a cyclomatic radical is substituted with univalent aliphatic radicals, these substituents can be radicals having from 1 to about 12 or more carbon atoms selected from the group consisting of alkyl, alkenyl, aralkyl and aralkenylf Thus, when these substituents are univalent aliphatic radicals, they can be alkyl radicals, such as methyLethyl, n-propyl, isopropyl, n-butyl, isobtuyl, secbutyl, n-amyl, the various positional isomers thereof, as for example,r2-methylbutyl; l,l-dimethylpropyl; l-ethyl- -propyl, and the corresponding straight and branched chain isomers-ofhexyl, heptyl, octyl, .nonyl, decyl, undecyl, dodecyl, tetradecyl, hexadecyl, nondecyl, eicosyl, and the like. Likewise, ,the univalent aliphatic substituent can 'be an alkenyl radical, such as ethenyl, A -propenyl, A -propenyl, isopropenyl, A butenyl, Albutenyl, A -butenyl, and the branched chainisomers thereof as A -isobutenyl, A -isobutenyl, A sec-butenyl, A -sec-butenyl, A -pentenyl, M-pentenyl, and the branched chain isomers thereof A hexenyl, A -hexenyl, A -hexenyl, and the branched chain isomers thereof, including 3,3-dimethylA -buteny1; 2,3- dimethyl-n -butenyl; and l-methyl-l-ethyl-A propenyl; and'the various isomers of heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, heptadecenyl, octodecenyl, eicosenyl, and the like.

When the organic'radical substituted in the cyclomatic group is a univalent aliphatic radical, it can be an aralkyl radical such as, forexample, benzyl, u-phenylethyl, 5- -phenylethyl,-a-phenylpropyl, oz-phenylisopropyl, a-phenylbutyl, a-phenylisobutyl, fi-phenyl-t-butyl,a'-naphthyl methyl, fl-naphthylmethyl, 'a-(d-naphthyD-ethyl, B-(a'-naph- -thyl)-ethyl, ct-(oc'IlflPhthYl) -prop-yl, -a-( 6naphthylisopropyl, 'y-(d-naphthyl) -butyl, -a-'(a-naphthyl)isobutyl, 13-03- -naphthyl) -sec-butyl, the corresponding aand fY-naphthyl derivatives of n-amyl and the like. Other such aralkyl radicals include'thea -,B'-, and 'y-anthryl derivatives of 'alkyl radicals, such as a'-anthrylmethyl, ,fi-(y anthryhethyl, 'A- 8-anthryl)-2-n1ethylamyl, and the like; and the corresponding alkyl derivativesofphenanthrene, fluorene, acenaphthene, chrysene, pyrene, triphenylene, naphthacene, etc. The univalent aliphatic radical can be an -aralkenyl radical, such as 'a-phenylethenyl, S-phenylethenyl, -a-phenyl-A -propenyl, and-the phenyl derivatives of the isomers of butenyl, pentenyl, heptenyl,- and'the like,

' up to about eicosenyl. Other such arylalkenyls include *be cycloalkyl radicals, such as, for example, cyclopropyl, cyclobutyhcycloamyl, cyclohexyl, cyclononyl, cyclodecyl,

'cyclododecyl, 'cyclooctodecyl, cycloeicosyl, and such cycloaliphatic radicals as a-cycloproptyl-ethyl, u-cyclobutyl- 'propyl, and the like. Similarly, the alicyclic radical substituents can be cycloalkenyl radicals suchas woyclohexylethenyl, a-cycloheptyl A propenyl, '18 -'cyclooctyl A propenyl, a-methylene-fi-cyclododecylethyl, and the like.

When the organic radicals substituted in the cyclomatic groups are imivalent aromatic radicals, they can be se- "lected from the group consisting of aryl and alkaryl radicals. Thus, these 'univalent aromatic radicals canbe aryl radicals, such as, for example, phenyl, naphthyl, anthryl, and the like including the various monovalent radicals'of such aromatics as indene, acenaphthene, fiuorene, naphthacene, chrysene, and the like. Moreover, these univalent aromatic radicals can be alkaryl radicals such as, for example, tolyl, 3,5-Xylyl, p-cumenyl, mesityl, ethylphenyl, 2-methyl-a-naphthyl, l ethyl-B-narphthyl, and the like.

Having amply described the meaning of the term organic radical, the discusion with regard to cyclomatic 4 radicals has been facilitated. As stated hereinabove, the cyclomatic groups of the compounds of the present invention can be represented by four general formulae. The first class of cyclomatic radicals can be represented by the general formula I I wherein each of R R ,R R andR can be the same or different and is selected from the group consisting of hydrogen and organic or hydrocarbon radicals "having from about 1 to about 12 or more carbon atoms. Illustrative examples of such cyclomatic radicals include cyclopentadienyl; methylcyclopentadienyl; -l,-2-dimethylcyclopentadienyl; ethylcyclopentadienyl; 'l,3;4 fi ipropylcyclopentadienyl; l,S-dipentylcyclopentadienyl; -l-meth-yl 3 t-butylcyclopentadienyl, isopropenylcyclopentadienyl; l,'2- di(A isobutenyl)cyclopentadienyl; 1-methyl-3 -"(A 'p'entenyl) cyclopentadienyl; 3-'(,9-phenylethy-1)-cyclopentadienyl; 3- cyclohexylcyclopentadienyl; 2-phenylcyclopentadienyl; 1- ethyl-3-(a-methyl-cyclopentadienyl; 2 (-0 -tolyl cyclopentadienyl; 1- acetylcyclopentadienyl; and the 7 like.

The second type of cyclomatic radicalis the 'indenyltype radical represented by thegcneral formula 7 R1 11 wherein each of 11 ,11 R 4, 1;, man, can be the :same or difierent and is-selectediromthe group consisting cof hydrogen and organic and hydrocarbon radicals hav- 1R1 Ba Rs 7 111 wherein each of R R 1 11 -R ,':R ,rR' and R, can be the same or'difierent and is selected' fromathegroup'consisting of hydrogen and organicand hydrocarbonradicals havingfrom 1 to about 1-2 ormorecarbon atoms. .11- lustrative examples ofsuch radicals include fiuorenyl; 3- ethylfluorenyl; 4,5-dipropyl fluorenyl;: 9qnethylfluorenyl; 6-ethenylfluorenyl; 4-benzylfluorenyl; 2-m-to1ylfluorenyl, and the like.

Thefourth type "of cyclomatic radical, 'that is, a radical containing the cyclopentadienyl moiety can be repre- I sented by the general formula 'the class consisting oi hydrogen andcrganic radicals.

Thus, when a is zero each of-the carbon atoms designated as Zand *3 have attached thereto a monovalent .5 radical'selected from the class consisting of hydrogen and organic radicals. Furthermore, the monovalent radicals so attached can be the same or difierent. The same discussion applies to each of the carbon atoms designated as 4 and 5 when b is zero. Illustrative examples of this type of cyclomatic radical include 4,5,6,7,-tetrahydroindenyl; 1,2,3,4,5,6,7,8 )ctahydrofluorenyl; 3-methyl-4,5, 6,7-tetrahydroindenyl, and the like.

Non-limiting examples of the compounds of this invention in which the cyclomatic radical has the configuration shown in Structure I above are tris (cyclopentadienyl) boron;

tris (methylcyclopentadienyl) boron;

tris (ethylcyclopentadienyl boron;

tris (propylcyclopentadienyl)boron;

tris (butenylcyclopentadienyl)boron;

tris t-butylcyclopentadienyl) boron;

tris (hexylcyclopent adienyl) boron;

tris (cyclohexylcyclopentadienyl) boron;

tris (heptylcyclopentadienyl) boron;

tris decylcyclopentadienyl) boron;

tris dodecylcyclopentadienyl) boron;

tris l ,2, 3 ,4-tetramethylcyclopentadienyl) boron; tris( 1,2,3,4,5-pentamethylcyclopentadienyl) boron; tris( 1 ,3-dibutylcyclopentadienyl) boron;

tris (=1 ,2-dipropyl-3 -cyclohexylcyclopentadienyl)boron; tris (tolylcyclopentadienyl) boron;

tris 1,3-diphenylcyclopentadienyl) boron;

tris acetylcyclopentadienyl) boron;

bis cyclopentadienyl) (methylcyclopentadienyl)boron; cyclopentadienyl-bis (indenyl) boron;

tris cyclopentadienyl) aluminum;

tris (methylcyclopentadienyl) aluminum;

tris ethylcyclopentadienyl) aluminum;

tris (propylcyclopentadienyl) aluminum;

tris (butenylcyclopentadienyl) aluminum;

tris t-butylcyclopentadienyl) aluminum;

tris (hexylcylopentadienyl) aluminum;

tris cyclohexylcyclopentadienyl) aluminum;

tris cyclohexylcyclopentadienyl) aluminum;

tris (heptylcyclopentadienyl) aluminum;

tris decylcyclopentadienyl) aluminum;

tris dodecylcyclopentadienyl) aluminum;

tris l ,2,3 ,4-tetramethylcyclopentadienyl) aluminum; tris( l,3-dibutylcyclopentadieny1) aluminum;

tris(,1,2-dipropyl -j 3 cyclohexylcyclopentadienyl) alumihum; l I, tris (tolylcyclopentadienyl) aluminum;

tris l,3 diphenylcyclopentadienyl) aluminum;

.tris acetylcyclopentadienyl) aluminum;

bis c y clop entia dienyl (methylcyclopentadienyl) p aluminum;

cy'elopentadienyl-bis (indenyl) aluminum;

tris cyclopentadien'yl) gallium;

,tris(i'ndenyl) gallium;

t'ris (flnorenyl).gallium;' tri s(cyclopentadienyl) indium; tris(methylcyclopentadienyl)indium; tris(indenyl)indium;

tris(cyclopentadienyl)thallium;

; tris (methylcyclopentadienyl) thallium; t'ris(indenyl)thallium,

and the like.

Other examples of compounds having the configuration 'of Structure 11 given hereinabove are tris(indenyl)boron; "tris(3-methylindenyl)boron; tris(3-ethenylindenyl)boron; tris (2,3-dimethylindenyl)boron; tris 1,3-diethyl1'ndenyl) boron; tris(1',7-diisopropylindenyl)boron; tris(1,2,3,4,5,

tion of Structure 111 above are tris(fluoreny'1)boron; his- 6 (3 ethylfluorenyl) aluminum; tris(4 propylfluorenyl)- aluminum; tris(2,3,4,7 tetramethylfluorenyl) aluminum, and the like.

Examples of compounds having the configuration of Structure IV above are tris (4,5 ,6,7tetrahydroindenyl) aluminum; tris( l,2,3,4,5,6,7,8-octal1ydrofluorenyl) aluminum; tris( 1,4,5 ,8-tetrahydrofluorenyl) aluminum,

and the like.

The reaction is preferably carried out in the presence of a suitable, preferably non-aqueous, solvent, examples of which are hydrocarbons, such as benzene, cyclohexane, isobutylene, toluene; and ethers, such as diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol methylphenyl ether, methylphenyl ether, tetrahydrofuran, dioxane, dodecyl ether, etc. In other words, hydrocarbon and ether solvents having up to about 20 carbon atoms may be employed.

The cyclomatic group III-A element products can be separated from the reaction mixture by solution in a solvent, such as ether, and the removal of the solid impurities -by filtration, centrifugation, and the like. The product can also be separated from the reaction mixture by .vacuum distillation or selective solvent extraction. The solvent may be removed from the product by fractional distillation and the product further purified by fractional distillation or sublimation. The method of preparation is'further illustrated in the examples below.

When the tris(cyclomatic)metal compounds of the invention are employed to form cyclomatic manganese compounds, a wide variety of manganese salts can be used for this reaction. 7

The manganese salts employed are salts of organic or inorganic acids, preferably the respective manganous salts. Examples of these manganese salts are manganous acetate, manganous benzoate, manganous carbonate, manganous oxalate, manganous lactate, manganous nitrate, manganous phosphate, manganous sulfate, manganic phosphate, manganous fluoride, manganous chloride, manganous bromide, manganous iodide, and the like. In addition, manganese salts of ,B-diketones, such as tris(2,4 pentanedione)manganese' and tris(2,4 hexanedione)manganese may also be employed, as well as manganese salts of fi-keto esters, such as the manganese salts of-ethylacetoacetate, and the like. An example of the processv employed is the reaction of tris(cyclopentadienyl)aluminum with manganous halide to give bis(cyclopentadienyhmanganese. Cyclomatic group III-A element compounds are also reacted with naturally occurring manganese ores, such as manganosite (MnO), manganese dioxide (M1102), manganic sesquioxide (Mn O manganous sulfide (MnS), manganic sulfide (MnS rhodochrosite (MnCO and the like, to give bis(cyclomatic)manganese compounds such as bis(methylcycl0- pentadienyl)manganese, etc.

EXAMPLE I Tris(cyclopentadienyl) aluminum To a reaction vessel equipped with a stirrer and a thermometer, and previously purged with dry nitrogen was added 8.1 parts (0.302 mole) of finely ground aluminum metal. The aluminum was treated with a diethyl ether solution of anhydrous hydrogen chloride for the purpose of cleaning and activating the surface of the aluminum. The reaction was allowed to continue until all of the metal became dispersed in the foamy mixture. The ether was then removed by three washings with toluene and finally parts of toluene was added as a solvent for the reaction,

With stirring, 25 parts (0.0755 mole) of bis(cycl0- pentadienyl) mercury was then added which had been previously prepared according to the method of Wilkinson and Piper, J., Inorg. Nucl. Chem. 2, 32 (1956), from cyclopentadienyl sodium and mercuric chloride. After a 3i)- 7 minute-addition period'during which the'temperature rose as high as 45 C., stirring was-continued for an additionall hour at room temperature. A test for mercuric ion in solutionwas negative.

The reaction mixture was thencentrifuged to remove suspended aluminum. Solvent was removed by evaporatron at room temperature.

There was obtained 10.7 parts (95.6% yield) of the grey solid tris(cyclopentadienyl) aluminum which melted at 50f60 C. It was soluble in benzene and toluene. Aip'ortion, on exposure to air, did not spontaneously inflame. Instead, it 'gra'dually'whitened, indicating formation of aluminum *oxide and hydroxide due'to attack of atmospheric oxygen'and moisture. Upon treatment with water, white aluminum hydroxide was formed. This was soluble in dilute acid. The product on aging, stored under nitrogen, showed no tendency to discolor or change in character. The analysis of the product showed 12.1 percent aluminum, the theoretical being 12.24 percent. 7 The tris(cyclopentadienyl)aluminum (1 mole) preparedabove is reacted with stoichiometric quantities of anhydrous manganous chloride at 165 9 C. indiethylene glycol dimethyl ether (lmole). The reaction mixture was stirred throughoutthe reaction. The bis(cyclopentadienyl)manganese so formed is thereafter reacted with carbonmonoxide (500'p".s.i.g.) at 190 C. to produce cyclope'ntadienyl manganese tricarbonyl. This product, after purification by distillation, is then blended in gasoline (0.2 gram manganese metal/gal. of gasoline) to raise the octane number of the gasoline 2 octane numbers.

EXAMPLE II p T ris(methylc yclopentadienyl) aluminum Example I is repeated except 'that bis(methylcyclopentadienyhmercury is employed instead of bis(cyclopentadienyl) mercury and the aluminum was activated by being employed in excess in the previous example. In this example, 'benzene is employed as the solvent. The tris- .(methylcyclopentadienyl)aluminum isrecovered in-good yield.

EXAMPLE 111 T ris(indenyl aluminum Example I is repeated except that bis(indenyl)mercury employed instead of bis(cyclopentadienyl)mercury, and hexane -is employed as' the solvent. 'Very satisfactory yields of the tris(indenyl)aluminum are obtained.

EXAMPLE IV Tri.( cyclopentadienyl) boron 'Fluorenylmagnesiumbromide (80.7 parts) dissolved :in 800 parts of diethyl ether is added to 17.6 parts of gallium trichloride dissolved in 50 parts of diethylether. 'The reaction mixture is heated for one hour at reflux temperature and the tris(fluorenyl) gallium is recovered, -as'in ExampleIV, in good yield.

EXAMPLE V1 T ris(n-octylcyclopentadienyl)indium "Indium metal (11.5 parts) is added to 200 parts of n- -o'ctylcyclopentadiene. The indium metal was pretreated with aluminum triethyl to activate themetal. Theactivation isconducted at 70 C. and the indium: :metal -is r separated from the excess 'triethylfiand trans ferred to the reaction vessel containing the n-"octylcyclo pentadiene under an inert atmosphere. 'l'his'reaction mixture is then' heated to 'a'temperaturenf 125*0. for five hours and the tris(n-octylcyclopentadienyl)indium is thereafter recovered in excellent yieldiby distilling "oii-the excess n-octylcyclopentadieneat1 name-Hg pressure.

EXAMPLEIVII Tris (cyel0peniudienylflhdllium Example I is repeated except that'thallium-metal (a1- loyed with 5% of its weightofcopper metal) isreacted with tris(cyclopentadieny1)zinc. metalis employed in a 3-moleexcess. -The reactionisconducted in dicyclohexylamine solvent at a'temperature of 'C. The tris (cyclopentadienyl) is recovered as. a complex with the amine solvent.

EXAMPLE iViII Bis(cyclopentadienyl)methylcyclqpentailienyl aluminum A mixture of cyclopentadienyl sodium (2'moles) and methylcyclopentadienylsodium. 1 mole) is dissolved in diethylene'glycol 'dibutyl ether and reacted-With aluminum in accordance with the procedure .of. Example I. A good yield of bis(cyclopentadienyl) methyleyclopentadienyl aluminum isob'tained.

u v EXAMPLE 1X.

Cyclopentadienyl lithium Cycl'openta'dienyl lithium was-obtained byipre'paringnbutyl lithium and reacting'this compoundwith-cyclopentadiene. According to this process, 68.5 parts-of 114mm bromide was added to 8.6partsdf metal in anhydrous diethyl ether-at a temperature of 10 C. The resultant ether solutiouof n butyl "lithium was filtered and then added to 20.4. parts of cycl'opentadiene in ether. The product, cyclopentadienyl lithium settled out as a white solid, the completion ofthe reaction being evidenced by the cessation of butane evolution. The procedure followed in the above synthesis ;was that-described in Organic Reactions, voIume VIL-PPQSSZ-BSS, John Wiley and Sons, Inc., New York (1951)...

Tricyclopentadienyl boron The cyclopentadienyl lithium 'in ether, prepared as above, was slowly added with agitation"to"15.2 parts of fluids, means for refluxing liquids, temperature measuring devices, means for regulating temperature, and fitted with a mechanical agitator. Thereaction resulted in the for-- mation of an orange coloredproduct. Th'e'ether-soluble product was removed from the unnamed ether insoluble cyclopentadienyl lithium by filtration, Ammonia was bubbled through the ether ,solufion to remove any unreacted boron trichloride which'settled out as 'a solid ammonia addition compound. The 'e therllayer was fevaporated leaving an orange solid. 'Ihis produet turned bluegreen on exposure to air. The ratioof'thefpercentagefby weight of carbon to the total of carbon, hydrogen and boron is 86 percent, which indicates "that the product obtained in this reaction is (C H B, calculated 8719c!- centcai-bon. I

Equally good-results areobtained when the teaching of the above example-is employed vinreactingother cyclopentadienyl-type alkali metal compounds with boron tri- Ihalides as, for example, the reaction' between l-methyl 'cyclopentadienyl sodium with boronitribromide in benzene toproduce :tris(-1-methyl cyclopentadienyDboron, the :re-

.action :between -:3'-phenyl 'cyclopent'adienyl potassium with boron trifluoride in anhydrous anisole to produce tris(3- .ph'enyl :c-yclopent'adienyDboron, the reaction between in- -.:denyl rubidium with boron triiojdideiin a solvent com- 9 posed of a mixture of diethyl ether, benzene, and hexane to produce triindenyl boron, and the like.

Tris(2-benzyl cycldpentadienyl)aluminum can be obtained by the reaction of 2-benzyl cyclopentadienyl potassium with aluminum chloride.

This application is a continuation-in-part of our 00- pending application, Serial No. 297,392, filed July 5, 1922 and application Serial No. 417,920, filed March 22, 19 4.

We claim:

1. A cyclopentadienyl element compound having the general formula:

wherein R is a cyclopentadienyl hydrocarbon group and M is a group III-A element, the element M being bonded to a cyclopentadienyl ring carbon of the cyclopentadienyl group, said cyclopentadienyl group containing from 5-17 carbon atoms.

2. The compound of claim 1 wherein the element is aluminum.

3. Tris(cyclopentadienyl)aluminum.

4. Tris(methylcyclopentadienyl)aluminum.

5. The compound of claim 1 wherein the element is boron.

'6. Tfis(cyclopentadienyl)bdron.

7. Tris(methylcyclopentadienyl)boron.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A CYCLOPENTADIENYL ELEMENT COMPOUND HAVING THE GENERAL FORMULA: 